Questions tagged [key-distribution]

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Why Nonces and timestamps are used in Public key authority?

why the nonces(N1 and N2) and Timestamps(T1 and T2) are used in Public key Authority? which of them prevent replay attack?
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41 views

Decentralized / Distributed Private Key Generation between Untrusted Parties?

I found an interesting concept in this paper, page 13, (Link to the paper) called "Decentralized private key generation", as follows: "Decentralized private key generation – Multiple Enigma nodes ...
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1answer
70 views

Protocol that generates keys every 2 minutes using KDC

I am using a Key Distributed Center (KDC) and a key distribution protocol such as Kerberos. In order to limit the amount of ciphertext produced with the same key, I want to renew the session keys ...
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0answers
38 views

Confirmation signature - Improved Feldman VSS

I am working through the implementation of A Distributed Private-Key Generator for Identity-Based Cryptography. In the paper (Figure 1, page 8) the validation of a share by a node says that once ...
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0answers
55 views

Reduction from integer factoring to computational Diffie Hellman

The computational Diffie Hellman (CDH) problem for ${\mathbb{Z}}^*_p$ is given a prime $p$, a generator $g$ of ${\mathbb{Z}}^*_p$, and a pair $(g^i, g^j)$ to compute $g^{ij}$. The value $g$ is called ...
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1answer
173 views

Is E91 safer than BBM92?

I would like to compare the security of these two QKD protocols which both use entangled photons that are distributed between the users Alice and Bob. In the case of E91, the photon is measured ...
2
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1answer
167 views

Why is this voting system not secure?

Why not have each person simply treated as a counterparty to an off-the-record chat? People show up in groups and show ID which is cross referenced against a central database to prevent sybil attacks ...
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1answer
145 views

Implement the joint-feldman DKG algorithm

I am looking for a work implementation of joint-feldman DKG or at least some library that can help me in the implementation Anyone can help me?
4
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1answer
121 views

Understanding Quantum Key Distribution

I have watched dozens of videos on YouTube talking about Quantum Cryptography and how the BB84 algorithm works. However none of them bothered himself to explain how quantum key exchange process works ...
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1answer
77 views

Does an EC signature preserve entropy?

Assume I have a perfect source of entropy, which is unknown to me, and is used to generate a private key (also unknown to me, but usable). If I make a signature with this unknown private key on a ...
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3answers
799 views

Why in one time pad must the key distribution to be truly random

One time pad required a truly random key. Why canwt it be a psudo-random key? For example, if the key distribution is that for each bit the probability to get 1 is 0.6 and the probability to get 0 is ...
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1answer
212 views

Multi party anonymous key distribution

Consider a protocol, wherein Alice wants to send a message $M$ to many friends $F_1, F_2, \dots F_n$, from whom she has (some form of) public keys ($e_{F_i}$, with private key $d_{F_i}$). She does not ...
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4answers
3k views

What makes Quantum Cryptography secure?

This is my current understanding of how Quantum Cryptography works: (The first bit is Quantum Key Distribution) Alice sends a beam of photons to Bob through a quantum channel such as an optical fiber....
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1answer
786 views

Key Exchange & key Distribution in symmetric key cryptography

I want to know whether there is a difference between key exchange & key distribution in private key cryptography as well as public key cryptography? or is it the same term?
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1answer
147 views

Number of uniform n-bit strings

In the set of 2^n binary strings on n-bits, how many strings have exactly equal number of 0s and 1s.
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0answers
134 views

ABE Cryptography - Send user private key

I am studying Attribute Based Encryption. Now my study concerns CP-ABE scheme. The authority make users private keys using attributes and a Master Secret Key (of Authority). How can the authority send ...
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1answer
1k views

Key Distribution vs Key Management?

What exactly is the difference between "Key Distribution" and "Key Management"?
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2answers
5k views

How does the sender obtain the receiver's public key?

Cryptography process includes encryption and decryption process. In public key cryptography public key of receiver is being used for encryption. I want to know how public key of receiver is sent to ...
2
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1answer
327 views

Dividing a secret into multiple nodes in a blockchain kind of system with time-release?

I would like to have these features and want to ask if it is theoretically possible: a) There is custom software running on nodes in a blockchain style b) A secret is kept in the blockchain that ...
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0answers
42 views

Security or not in Key distribution

For example, There are 3 clients. I want to deliver specific value $x$ to all clients. $x\leftarrow {0,1,2,...,q-1}$ where q is a large prime number. By using function $f(x)=x*y_{i}*z_{i}$ where i=...
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419 views

How does Blom's scheme work?

How does Blom's scheme work? Is the polynomial expression of it a normal one? A few additional questions: How big does the prime modulus need to be? Can it be bigger than the size of the derived key?...
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3answers
406 views

Possible to generate a one time secret which all nodes on the distributed network can know but cannot pre compute

I have a distributed P2P network. Everyday, I want each node to have a secret which is only valid for that day, while each of the other remaining nodes on the network will be able to calculate the ...
3
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1answer
293 views

What are the current known weaknesses/attacks on quantum key distribution?

I am writing a paper on the implementation of QKD in the future. I want to know if there are any viable attacks on the BB84 protocol or QKD in general? I know of the Photon Number Splitting attack or ...
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1answer
150 views

One time pad ciphers in emails

In order to achieve very high security for privacy, would it be cryptographically secure to use one time pad ciphers in emails? The distribution of the keyword would pose no problems since I would ...
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1answer
124 views

How are onetimepads distributed?

OTP encryption is unbreakable as it seems. I have read some stuff (wiki, blogpost, etc.) but i would not find any information how they are used. If i wanted to create a messenger service, how would i ...
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2answers
851 views

Is Pseudo-Random Generator (PRG) in OpenSSL uniformly distributed?

I need to know can we use PRG of OpenSSL as a PRF?
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1answer
1k views

Problem in understanding Blakley's Secret Sharing Scheme

I need to implement Blakley's Secret Sharing Scheme. I have read below mentioned two research papers but still unable to understand how to implement it. Safeguarding cryptographic keys Two Matrices ...
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3answers
401 views

Updating the secret key used for HMAC

I am designing a distributed system, composed by a set of physically distributed embedded devices (8 bit cores with less than 1 KB of RAM). The devices need to be able to authenticate the originator ...
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0answers
158 views

How to distribute symmetric key between $n$ entities?

If there are $n$ servers for broadcasting a symmetric key in such a manner that following holds: No server alone can find the key $K$ alone. Any two servers can pass $k_i$ and $k_j$ such that $K=f(...
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1answer
101 views

In Needham Schroeder key distribution what happens if responder's part is not encrypted in step 2 with Kbs but encrypted instead by Kab in step 3

The Needham-Schroeder protocol is: 1 A→S:A,B,Na 2 S→A:{Na,B,Kab,{Kab,A}Kbs}Kas 3 A→B:{Kab,A}Kbs 4 B→A:{Nb}Kab 5 A→B:{Nb−1}Kab Here Na and Nb are nonces. Kab is the key between a and b Kas is ...
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1answer
283 views

Traitor-tracing PRF

I'm looking for a pseudorandom function (PRF) with "traitor-tracing" properties. More specifically, I'd like there to be multiple equivalent keys, so I can give different parties different keys, but ...
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1answer
248 views

Combining two hashing functions

I have been working on a Bloom Filter implementation recently and after a discussion with a co-worker about how many hashing functions to use I told him I was limited with using hashing functions that ...
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2answers
20k views

How is the key shared in symmetric key cryptography?

Symmetric key cryptography is an encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Is the key public or it is ...
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1answer
897 views

Proof of correct construction of a private key in distributed cryptography

In an exponential ElGamal encryption scheme where the key generation is done in a distributed way among $n$ trustees we have that each trustee $i$ (where $1 \leq i \leq n$): Selects a private key ...
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1answer
407 views

Public Keys on Social Media

Is there any problem with using social media (i.e. Facebook) as a directory of public keys? For example, couldn't Alice put a note containing $(g^a \bmod p, g, p)$ on her Facebook page so she could ...